You won't and I can prove that.
At least when they are placed and designed like I suggested.
The one below have to be like the Pandora ones.
The one above have to come out a little. To not damage them over time they have to be rounded a little like the 3DSxl ones.
It will work without any trouble that way.
If they are both the same then it's likely to fail I think.
I respect your design idea but again, it would be so or so way more complicated than a simple side by side design.
I'm sure it could be possible to make an vertical array but this would need alot of design and testing to find the perfect shape and placement which leads to alot of time and money consumpting which should be avoided. Better put these ressources into the much more important parts like general case design, perfect D-Pad and so on.
I have no prove of course but my gut feelings say that there will be alot of trouble incoming to get a comfortably working, vertical shoulder button array. :unsure: